[PATCH 2/8] powerpc/dma: properly wire up the unmap_page and unmap_sg methods

[Christoph Hellwig]

The unmap methods need to transfer memory ownership back from the device
to the cpu by identical means as dma_sync_*_to_cpu.  I'm not sure powerpc
needs to do any work in this transfer direction, but given that it does
invalidate the caches in dma_sync_*_to_cpu already we should make sure
we also do so on unmapping.

Signed-off-by: Christoph Hellwig <hch at lst.de>
---
 arch/powerpc/kernel/dma.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/kernel/dma.c b/arch/powerpc/kernel/dma.c
index dbfc7056d7df..d442d23e182b 100644
--- a/arch/powerpc/kernel/dma.c
+++ b/arch/powerpc/kernel/dma.c
@@ -210,10 +210,15 @@ static int dma_nommu_map_sg(struct device *dev, struct scatterlist *sgl,
 	return nents;
 }
 
-static void dma_nommu_unmap_sg(struct device *dev, struct scatterlist *sg,
+static void dma_nommu_unmap_sg(struct device *dev, struct scatterlist *sgl,
 				int nents, enum dma_data_direction direction,
 				unsigned long attrs)
 {
+	struct scatterlist *sg;
+	int i;
+
+	for_each_sg(sgl, sg, nents, i)
+		__dma_sync_page(sg_page(sg), sg->offset, sg->length, direction);
 }
 
 static u64 dma_nommu_get_required_mask(struct device *dev)
@@ -247,6 +252,8 @@ static inline void dma_nommu_unmap_page(struct device *dev,
 					 enum dma_data_direction direction,
 					 unsigned long attrs)
 {
+	if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC))
+		__dma_sync(bus_to_virt(dma_address), size, dir);
 }
 
 #ifdef CONFIG_NOT_COHERENT_CACHE
-- 
2.19.2